nlohmann::basic_json<>::operator ValueType

get a value (implicit)

Synopsis

Declared in <nlohmann/json.hpp>

template<typename ValueType>
requires detail::conjunction <
                       detail::negation<std::is_pointer<ValueType>>,
                       detail::negation<std::is_same<ValueType, std::nullptr_t>>,
                       detail::negation<std::is_same<ValueType, detail::json_ref<basic_json>>>,
                                        detail::negation<std::is_same<ValueType, typename string_t::value_type>>,
                                        detail::negation<detail::is_basic_json<ValueType>>,
                                        detail::negation<std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>>,
#if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) && _MSC_VER >= 1910 && _MSC_VER <= 1914))
                                                detail::negation<std::is_same<ValueType, std::string_view>>,
#endif
#if defined(JSON_HAS_CPP_17) && JSON_HAS_STATIC_RTTI
                                                detail::negation<std::is_same<ValueType, std::any>>,
#endif
                                                detail::is_detected_lazy<detail::get_template_function, const basic_json_t&, ValueType>
                                                >::value
operator ValueType() const;

Description

Implicit type conversion between the JSON value and a compatible value. The call is realized by calling get() const.

Linear in the size of the JSON value.

{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers, (2) A JSON array can be converted to a standard std::vector<short>, (3) A JSON object can be converted to C++ associative containers such as std::unordered_map<std::string, json>.,operator_ValueType}

Exceptions

Name	Thrown on
`type_error.302`	in case passed type ValueType is incompatible to the JSON value type (e.g., the JSON value is of type boolean, but a string is requested); see example below

Return Value

copy of the JSON value, converted to type ValueType

Template Parameters